In order to register movement data and movement sequences, a method in which markers are attached to the body surface of a person is known in addition to pure image recording by means of one or more cameras. The moving person is recorded by a camera, with the markers being arranged at the fulcrums. The movements of the fulcrums in relation to one another are converted as a model in a computer following the registration by the camera apparatuses and imaged on a screen. Relative movements of body parts or body areas in relation to one another can be calculated from the model, wherein the calculation is based on model assumptions. Thus, the spinal column is usually assumed to be a rod, on which the pelvis and the shoulders are secured.
The latter method requires high instrument outlay, is generally only applicable in a specific surroundings situation and allows no, or only inaccurate, conclusions to be drawn about the actual twist within the spinal column or the actual displacement of individual body areas or body parts in relation to one another.
Document 10 2009 005 536 A1 relates to a rotational angle sensor for contactlessly determining the rotational angle of a rotational axis, comprising an optical radiation source and a detector, wherein a shadowing structure on a disk is arranged in the beam path between the radiation source and the detector, the position of which shadowing structure changes with the rotational axis. The shadowing structure is at least partly illuminated by the radiation from the radiation source, depending on the rotational angle of the rotational axis, and imaged on the detector. This allows measurement errors to be avoided or reduced and the rotational angle, to be registered, of the rotational axis to be established more precisely.